El Alto, Bolivia

At nearly 4,000 meters above sea level, El Alto is not for the faint of heart. With a population of 842,378, this rapidly growing city struggles to provide basic infrastructure like potable water and sewage systems to all its residents, especially in the sprawling outskirts. The thin atmosphere and freezing temperatures make daily life a persistent challenge.

On the plus side, the city's impressive cable car system connects it seamlessly with the economic center of La Paz. And a distinct local architectural style is emerging as El Alto rapidly modernizes. But the city's infrastructure woes, from water pollution to inadequate roads, remain a significant headache.

If you're the hardy type who can handle high altitudes and bureaucratic hurdles, El Alto might be worth considering. But for most, this bleak and rapidly expanding city on the Andean plateau is likely best avoided.